In cardiac arrest survival rates dramatically increase when bystanders are present and initiate Basic Life Support (BLS). However, even though serious efforts have been made, skill retention after a traditional time-based BLS course for laypeople remains suboptimal. In contrast, a mastery learning-based educational approach was shown to be efficacious and might be promising even for laypersons. Therefore the investigators aim to evaluate the impact of a mastery learning-based BLS course on skills retention of BLS in laypeople.